Through the end of the 2015 season, Jon Niese had spent his entire professional career in the New York Mets' organization. He has since been traded, of course, to the Pittsburgh Pirates for second baseman Neil Walker. But Niese entered last season with five full years of major league experience under his belt.
The results last year were neither spectacular nor terrible. Niese made 29 starts and four relief appearances. In the process, he threw 176.2 innings with a 4.13 ERA and 4.41 FIP. Adjusting for park and league, he pitched worse than the average major league pitcher by a decent margin.
It's hard to believe now, but the Mets started the 2015 season with a rotation that included Niese, Matt Harvey, Jacob deGrom, Bartolo Colon, and Dillon Gee. Things started looking a whole lot better over the course of the season, but Niese threw a significant portion of the Mets' innings last year.
By ERA, last year was Niese's worst season since 2011, as he had a 3.49 ERA—and looked like a league-average pitcher—between 2012 and 2014. Over the course of his time with the Mets, he consistently made between 24 and 30 starts per season, never eclipsing 200 innings in any given year but never dipping below 143 innings.
Late in the season last year, with the rotation much improved and the Mets headed for the playoffs, Niese approached Terry Collins about pitching out of the bullpen. He tried that role out in the final weeks of the regular season and stuck on the Mets' playoff roster working out of the bullpen. In 5.1 postseason innings, he had a 5.06 ERA, but it's not really fair to judge any player over such a small span of time.